Having described the expected spin rotation of relic neutrinos
we turn to their detection. The most promising approach
is to capture neutrinos on beta unstable nuclear targets. Particularly
favorable for detecting primordial neutrinos is the inverse tritium beta
decay (ITBD)[1]}, [2]}, \(\nu _e + ^3\) H\(\rightarrow ^3\) He + e\(^-\) 
the reaction inverse to tritium beta decay,
\(^3\) H \(\rightarrow ^3\) He + e\(^- + \bar{\nu }_e\) .
The ITBD would yield a distinct signature of a mono-energetic peak separated
from the endpoint of the tritium beta decay by twice the neutrino mass.
